Vanadium (V) at naturally occurring concentrations has been shown to be a significant inhibitor of (Na+, K+) ATPase, the enzyme responsible for the sodium pump reaction. Although there are conflicting data, it has been suggested that high vanadium levels may shut down the enzyme and lead to hypertension. Vanadium appears to cycle between the (IV) (inactive) and (V)(active) oxidation states. Glutathione is thought to be the reducing agent for the (V) to (IV) step, but little is known about the complexes that exist in the two oxidation states or how vanadium (IV) is oxidized. One study shows that glutathione also forms a complex with vanadium (IV). Due to the lack of knowledge of redox chemistry of vanadium in this system, this proposal is for fundamental studies of model complexes. Model complexes with glutathione, cysteine and penicillamine will be synthesized and characterized by electrochemical and spectroscopic techniques. The immediate goal is to elucidate the fundamental chemistry of such model systems. The ultimate goal is to mimic the effect of vanadium in vivo.